OBJECTIVE: To better delineate the spectrum of neurological complications of primary Sjögren's syndrome (PSS). METHODS: A detailed neurological investigation was prospectively performed in a group of 25 consecutive patients with PSS followed in an internal medicine department between June 1996 and December 1997 (Internal Medicine group). In addition, eleven patients with neurological complications of PSS were identified in the Neurological Department of the same institution during the same period (Neurological group). RESULTS: In the Internal Medicine group, neurological complications were discovered in 10/25 (40%) patients. Peripheral nervous system involvement was present in 4/25 patients from the Internal Medicine group and in 10/11 patients from the Neurological group and consisted mainly of axonal sensorimotor/sensory polyneuropathy. A motor neuron syndrome was identified in two patients. CNS involvement occurred in 7/25 patients from the Internal Medicine group and in 4/11 patients from the Neurological group. Three patients had spinal cord involvement. Cognitive dysfunction was the most frequent finding (5/25 in the Internal Medicine group, 3/11 in the Neurological group) characterized either by subcortical or corticosubcortical dysfunction. Cognitive impairment was not attributed to mood disturbance and was not associated with specific laboratory or radiological abnormalities. CONCLUSION: Neurological complications of PSS are frequent since they were present in 40% (10/25) of patients in a consecutive series of patients from a department of Internal Medicine. Although PNS involvement predominates, complications of PSS affecting the brain or spinal cord are not rare, with subcortical dysfunction as the main finding.